1. Field of the Invention
The present invention relates to an alternator driven by an internal combustion engine, for example, and in particular, relates to a stator construction for an automotive alternator mounted to an automotive vehicle such as a passenger car or a truck.
2. Description of the Related Art
FIG. 27 is an overall perspective of a stator for a conventional automotive alternator described in Japanese Patent Laid-Open No. HEI 9-103052.
This stator 140 includes: a cylindrical stator core 150 composed of a laminated core formed with a number of slots 150a extending axially at an even pitch in a circumferential direction; and a stator winding 170 wound onto the stator core 150. The stator winding 170 is a three-phase alternating-current winding composed of an a-phase alternating-current winding portion 170a, a b-phase alternating-current winding portion 170b, and a c-phase alternating-current winding portion 170c. a-phase, b-phase, and c-phase output wires Oa, Ob, and Oc and neutral-point lead wires Na, Nb, and Nc lead out of the respective alternating-current winding portions 170a, 170b, and 170c. In this example, the total number of slots 150a is thirty-six, which is one slot per pole per phase.
FIG. 28 is a winding diagram for the a-phase of the automotive alternator in FIG. 27.
The stator winding 170 is composed of the a-phase alternating-current winding portion 170a, the b-phase alternating-current winding portion 170b, and the c-phase alternating-current winding portion 170c, respectively, constructed by bundling round wire in which a copper surface is coated with insulation. The a-phase alternating-current winding portion 170a is constructed by wave winding into every third slot from slot number 1 to slot number 34. In this example, the wave winding folds back at slot 150a of slot number 34.
Moreover, although not shown, the b-phase alternating-current winding portion 170b and the c-phase alternating-current winding portion 170c are formed by offsetting each by one slot 150a. 
The method for manufacturing the stator 140 shown in FIG. 27 will now be explained.
First, a laminated body 183, shown in FIG. 29, is formed by laminating strip-shaped bodies having a width of approximately 20 mm and a thickness of approximately 1 mm, for example. Next, as shown in FIG. 29, the a-phase alternating-current winding portion 170a, the b-phase alternating-current winding portion 170b, and the c-phase alternating-current winding portion 170c, which are first formed in a flat shape, are installed in the laminated body 183 so as to be stacked one on top of another. Then, the stator 140 is prepared by bending the laminated body 183 into a cylindrical shape by means of a forming device (not shown) and welding core abutting portions 184.
In the conventional alternator shown in FIG. 27, because the a-phase alternating-current winding portion 170a, the b-phase alternating-current winding portion 170b, and the c-phase alternating-current winding portion 170c are offset by one slot 150a each when they are installed, portions of the a-phase alternating-current winding portion 170a, the b-phase alternating-current winding portion 170b, and the c-phase alternating-current winding portion 170c are not installed in the laminated body 183 before the laminated body 183 is bent into the cylindrical shape, as can be seen from FIG. 29, and these portions must be inserted into the slots 150a of the stator core 150 after the stator core 150 has been formed into the cylindrical shape, and a problem has been that there is a risk that the insulation coating on the strands of wire may be damaged by contact with opening portions of the slots 150a which have become narrower at that stage due to the formation of the stator core 150 into the cylindrical shape.
Another problem has been that the manufacturing process is complicated by the troublesome step of having to insert portions of the alternating-current winding portions 170a, 170b, and 170c into the slots 150a after formation of the cylindrical shape.
Moreover, even in the conventional alternator in which the number of slots is two per pole per phase (a total of ninety-six) and two sets of three-phase alternating-current windings are installed in a stator core, portions of each of the alternating-current winding portions must be inserted after the cylindrical shape is formed, leading to the same problems as the alternator shown in FIG. 27.
The present invention aims to solve the above problems and an object of the present invention is to provide an alternator in which the occurrence of damage to the insulation coating on the strands of wire during the manufacturing process is reduced and the manufacturing process is simplified.
To this end, according to the present invention, an alternator comprising:
a rotor for forming north-seeking (N) and south-seeking (S) poles alternately about a rotational circumference; and
a stator comprising:
a stator core surrounding the rotor; and
a polyphase stator winding installed in the stator core,
the stator core being formed with a number of slots extending axially at a predetermined pitch in a circumferential direction,
the stator core being provided with a core abutting portion extending axially such that the stator core becomes an annular shape by abutting end surfaces of a parallelepiped laminated body, and
the polyphase stator winding is provided with a winding connection portion axially aligned with the core abutting portion.